The present invention relates to novel vaccine formulations, methods for preparing them and to their use in therapy. In particular the present invention relates to novel formulations for treating Hepatitis infections and to combination vaccine formulations including a Hepatitis B vaccine component.
Viral hepatitis, caused by the A, B, C, D, and E hepatitis viruses, is a very common viral illness. Via the B and C viruses, in particular, it is also responsible for many cases of liver cancer. Thus the development of effective vaccines is critical and, despite notable successes, is still an on-going task. A review on modem hepatitis vaccines, including a number of key references, may be found in the Lancet, May 12th 1990 at page 1142 ff (Prof A. L. W. F. Eddleston). See also xe2x80x98Viral Hepatitis and Liver Diseasexe2x80x99 (Vyas, B. N., Dienstag, J. L., and Hoofnagle, J. H., eds, Grune and Stratton, Inc. (1984) and xe2x80x98Viral Hepatitis and Liver Diseasexe2x80x99 (Proceedings of the 1990 International Symposium, eds F. B. Hollinger, S. M. Lemon and H. Margolis, published by Williams and Wilkins).
As used herein the expression xe2x80x98hepatitis B antigenxe2x80x99 is used to refer to any antigenic material derived from a hepatitis B virus which may be used to induce immunity to the virus in humans.
Infection with hepatitis B virus (HBV) is a widespread problem but vaccines which can be used for mass immunisation are now available, for example the product xe2x80x98Engerix-Bxe2x80x99 (SmithKline Beecham plc) which is obtained by genetic engineering techniques.
The preparation of Hepatitis B surface antigen (HBsAg) is well documented. See. for example, Harford et al in Develop. Biol. Standard 54, page 125 (1983), Greg et al in Biotechnology, 5, page 479 (1987), EP-A- 0 226 846, EP-A-0 299 108 and references therein.
As used herein the expression xe2x80x98Hepatitis B surface antigenxe2x80x99 or xe2x80x98HBsAgxe2x80x99 includes any HBsAg antigen or fragment thereof displaying the antigenicity of HBV surface antigen. It will be understood that in addition to the 226 amino acid sequence of the HBsAg S antigen (see Tiollais et al, Nature, 317, 489 (1985) and references therein) HBsAg as herein described may, if desired, contain all or part of a pre-S sequence as described in the above references and in EP-A- 0 278 940. In particular the HBsAg may comprise a polypeptide comprising an amino acid sequence comprising residues 12-52 followed by residues 133-145 followed by residues 175-400 of the L-protein of HBsAg relative to the open reading frame on a Hepatitis B virus of ad serotype (this polypeptide is referred to as L*; see EP 0 414 374). HBsAs within the scope of the invention may also include the preS1-preS2-S polypeptide described in EP 0 198 474 (Endotronics) or analogues thereof such as those described in EP 0 304 578 (Mc Cormick and Jones). HBsAg as herein described can also refer to mutants, for example the xe2x80x98escape mutantxe2x80x99 described in WO 91/14703 or European Patent Application Publication Number 0 511 855 A1, especially HBsAg wherein the amino acid substitution at position 145 is to arginine from glycine.
Normally the HBsAg will be in particle form. The particles may comprise for example S protein alone or may be composite particles, for example (L*,S) where L* is as defined above and S denotes the S-protein of HBsAg. The said particle is advantageously in the form in which it is expressed in yeast.
Whilst experimental and commercially available Hepatitis vaccines, for example Engerix-B, afford excellent results it is an accepted fact that an optimal vaccine needs to stimulate not only neutralising antibody but also needs to stimulate as effectively as possible cellular immunity mediated through T-cells. International Patent Application No. WO 93/19780, discloses combination vaccines with a hepatitis B component based on a hepatitis B surface antigen, aluminium hydroxide and 3-de-O-acylated monophosphoryl Lipid A. A formulation comprising aluminium phosphate was not suggested.
Surprisingly, the present invention provides a formulation up to four times more potent than those described in WO 93/19780.
Accordingly the present invention provides a vaccine comprising a hepatitis B antigen in conjunction with 3-O-deacylated monophosphoryl lipid A (abbreviated herein to MPL) and aluminum phosphate.
3-O-deacylated monophosphoryl lipid A (or 3 De-O-acylated monophosphoryl lipid A) has formerly been termed 3D-MPL or d3-MPL to indicate that position 3 of the reducing end glucosamine is de-O-acylated. For preparation, see GB 2 220 211 A Chemically it is a mixture of 3-deacylated monophosphoryl lipid A with 4, 5 or 6 acylated chains. Herein the term 3D-MPL (or d3-MPL) is abbreviated to MPL since xe2x80x98MPLxe2x80x99 is a Registered Trademark of Ribi Immunochem., Montana which is used by Ribi to denote unambiguously their 3-O-deacylated monophosphoryl lipid A product.
Preferably in the compositions of the present invention small particle MPL is used. Small particle MPL has a particle size generally less than 120 nm. Such preparations are described in International Patent Application No. WO 94/21292.
GB 2 220 21 1A mentions that the endotoxicity of the previously used enterobacterial lipopolysacharides (LPS) is reduced while the immunogenic properties are conserved. However GB 2 220 211 cited these findings merely in connection with bacterial (Gram negative) systems.
Surprisingly, however, it has been found that vaccine compositions according to the invention comprising hepatitis B viral antigens have particularly advantageous properties as described herein.
A particular advantage is that the vaccine formulations of the invention are very effective in inducing protective immunity, even with very low doses of antigen.
The new vaccine formulations allow immunogenicity enhancements equivalent to currently available hepatitis B formulations after two doses. In particular equivalent levels of antibodies were obtained in a human clinical trial after two doses of vaccine compared with three doses of Engerix-B.
They provide excellent protection against primary infection and stimulate advantageously both specific humoral (neutralising antibodies) and also effector cell mediated (DTH) immune responses.
A further important advantage is that vaccine compositions according to the invention may also be used as therapeutic vaccines.
The MPL as defined,above will normally be present in the range of 10-100 xcexcg, preferably 25-50 xcexcg per doe,wherein the Hepatitis B antigen will be typically present in a range 2-50 xcexcg per dose and the aluminum phosphate will be in the range 500 xcexcg (Al 3+) per dose.
An embodiment of the invention is HBsAg S antigen (for example as in Engerix-B) in admixture with MPL and aluminum phosphate as described herein below.
A further specific embodiment of the invention is HBsAg antigen as (L*,S) particles, defined herein above, in admixture with MPL and aluminum phosphate.
The invention in a further aspect provides a vaccine formulation as described herein for use in medical therapy, particularly for use in the treatment or prophylaxis of hepatitis viral infections. In a preferred aspect the vaccine according to the invention is a therapeutic vaccine useful for the treatment of ongoing hepatitis B infections.
In another aspect, the hepatitis vaccine composition of the invention contains other antigens so that it is effective in the treatment or prophylaxis of one or more other bacterial, viral or fungal infections.
Accordingly the hepatitis vaccine formulation according to an embodiment of the invention contains at least one other component selected from other hepatitis antigens, in particular hepatitis A antigen, or non-hepatitis antigens which are known in the art to afford protection against one or more of the following: diphtheria, tetanus, pertussis, Haemophilus influenzae b (Hib), and polio. Antigens against meningitidis A, B, or C may also be included.
Preferably the vaccine according to the invention includes HBsAg as herein above defined.
Particular combination vaccines within the scope of the invention include a DTP (diphtheria-tetanus-pertussis) -hepatitis B combination vaccine formulation, an Hib-Hepatitis B vaccine formulation, a DTP-Hib-Hepatitis B vaccine formulation and an IPV (inactivated polio vaccine) -DTP-Hib-Hepatitis B vaccine formulation.
The hepatitis vaccine or the above combinations may advantageously include a component which is protective against Hepatitis A, especially the killed attenuated strain derived from the HM-175 strain as is present in Havrix.
Suitable components for use in such vaccines are already commercially available and details may be obtained from the World Health Organisation. For example the IPV component may be the Salk inactivated polio vaccine. The pertussis vaccine may comprise whole cell or acellular product, formulated with Diphtheria and Tetanus antigen such as Infanrix DTPa, which comprises three B. perrussis antigens:69KDa, pertussis Toxin (inactivated), and FHA.
In one aspect the hepatitis or combination vaccine according to the invention may be a paediatric vaccine.
Vaccine preparation is generally described in New Trends and Developments in Vaccines, edited by Voller et al., University Park Press, Baltimore, Md. U.S.A. 1979. Encapsulation within liposomes is described, for example, by Fullerton, U.S. Pat. No. 4,235,877. Conjugation of proteins to macromolecules is disclosed, for example, by Likhite, U.S. Pat. No. 4,372,945 and by Armor et al., U.S. Pat. No. 4,474,757.
The amount of antigen in each vaccine dose is selected as an amount which induces an immunoprotective response without significant, adverse side effects in typical vaccinees. Such amount will vary depending on which specific antigens, are employed. Generally it is expected that each dose will comprise 1-1000 xcexcg of total antigen, preferably 2-200 xcexcg. An optimal amount for a particular vaccine can be ascertained by standard studies involving observation of antibody titres and other responses in subjects. Following an initial vaccination, subjects may receive one or more booster doses, for example after 2 and 6 months.
In a further aspect of the present invention there is provided a method of manufacture of a vaccine effective in preventing or treating hepatitis infection, wherein the method comprises mixing the hepatitis antigen as defined herein with aluminum phosphate and MPL.
Using this method one or more additional components are preferably admixed with HBsAg to provide a combination vaccine. Several methods of mixing the components may be used. In one method each antigen may be separately absorbed on aluminum phosphate and after a period of time MPL may be added to each before adding the blending solution.
It will be appreciated that the invention also provides a method of inducing neutralising antibody titres in the range of 10 mU for hepatitis B in a human susceptible to or suffering from hepatitis B infection by administering a composition as herein defined in no more than two doses.
In another aspect, the invention provides the use of a composition as herein defined for the manufacture of a vaccine for the induction of neutralising antibodies in the range of 10 mU for hepatitis B in humans preferably after no more than two doses.